Blue Ice of Surprise Glacier

September 20, 2007


Provided and copyright by: Robert Wagner, Max-Planck-Institute for Physics, Munich
Summary authors & editors: Robert Wagner

Glaciers are abundant in south-central Alaska's Prince William Sound. One showcase glacier is Surprise Glacier, shown above. Note its bluish ice formations. Is glacier ice really blue? No, it just appears to be blue because the longer wavelengths of light (reds and yellows) are more readily absorbed by thick ice than are the shorter wavelengths (blues and greens). Thus, the longer light travels in ice, the bluer it appears. In contrast to thick ice, sunlight does not penetrate very far into snow, therefore it appears white. However, when you poke a hole into deep, fresh snow (more than about 0.3 m or 1 ft in depth), bluish light will emerge. Photo taken on May 25, 2007. See also the for July 27, 2007.

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